This invention relates to a flywheel assembly having a fluid vibration dampening mechanism which includes a slider disposed in a fluid filled chamber within the vibration dampening mechanism.
Flywheel assemblies used with automobile engines are disposed between the engine of the automobile and the transmission. The flywheel assembly includes a first flywheel and a second flywheel, a driven plate that rotates integrally with the second flywheel, an elastic coupling mechanism that elastically connects the first flywheel and the driven plate circumferentially, and a viscous dampening mechanism at least partially disposed in a fluid chamber formed between both flywheels. The first flywheel is connected to the crankshaft of the engine. The clutch is coupled to the transmission and is engagable with the second flywheel. A choke is formed in the fluid chamber of the viscous dampening mechanism with allows the passage of fluid in response to relative rotation between the first flywheel and second flywheel. Viscous resistance occurring while fluid passes through the choke dampens torsional vibrations.
The fluid chamber of the viscous dampening mechanism includes a fluid chamber housing fixed to the first flywheel. An annular convex connecting portion is formed on the inner peripheral edge of the fluid chamber housing. This convex connecting portion seals the inner periphery of the fluid chamber by coupling to a concave connecting portion of the driven plate.
The outer peripheral edge of the driven plate is inserted into the fluid chamber housing from the inner peripheral side and a plurality of projections are formed at intervals circumferentially. Further, a cap shaped slider is arranged which covers the projections of the driven plate from the outer peripheral side. The slider material can freely move circumferentially within an established angle range relative to the protrusions of the driven plate. Moreover, a choke is formed inside the viscous fluid chamber that allows the passage of fluid when the slider moves relative to the first flywheel.
In this type of construction, torque fluctuations in the engine of a vehicle are transferred to the flywheel as torsional vibrations. When a small torsional vibration of a torsional angle is transmitted to the flywheel, the slider repeats a reciprocating operation relative to the protrusions of the driven plate together with the first flywheel. During this time, fluid does not flow through the choke because there is no relative movement between the slider and the first flywheel. Consequently, torsional vibrations having a small torsion angle can be effectively dampened. When a large torsional vibration of a torsional angle is transmitted to the flywheel, the slider joins to the protrusions of the driven plate and rotates relative to the first flywheel. As a result, fluid flows through the choke causing a large viscous resistance. Consequently, torsional vibrations having a large torsion angle are effectively dampened.
Conventional flywheels often have the following problems: (1) Because the fluid chamber is formed by a fluid chamber housing, the number of parts increases making construction difficult and costly, (2) Because the driven plate and the housing join to form a seal, when a small torsional vibration is transmitted to the flywheel, rubbing between the driven plate and the housing creates friction. Therefore, the resistance ends up increasing. Further, when a large torsional vibration is transmitted to the flywheel, the seal properties of the seal connecting portion is not maintained and the viscous resistance cannot be made sufficiently large. The above results make it difficult to effectively dampen differing degrees of torsional vibrations.